Revert "build(deps): bump tracing from 0.1.37 to 0.1.38 (#109)"

This reverts commit b914250.

tracing 0.1.38 was yanked due to an unintended
backwards-incompatible change in a patch version bump:
tokio-rs/tracing#2578 (comment)

Author: JamesHinshelwood

Cargo.lock

@@ -42,5 +42,5 @@ tokio-stream = "0.1.14"
 toml = "0.7.3"
 tower = "0.4.13"
 tower-http = { version = "0.4.0", features = ["cors"] }
-tracing = "0.1.38"
+tracing = "0.1.37"
 tracing-subscriber = "0.3.17"